1.

An ideal battery passes a current of 5A through a resistor . When it is connected to another resistance of 10 Omega in parallel, the current is 6A . Find the resistance of the first resistor.

Answer»

Solution :For IDEAL battery internal resistance r=0
Resistance of first wire= `R_1`
Resistance of the second wire
`R_2 = 10 OMEGA`

Current through `R_1 ` in the first case `i_1 = 5A`
Current in the second case `i_2 = 6A`
Effective resistance in the second case `R= (R_1 R_2)/(R_1 + R_2)`
`V= I_1 R_1 and V= I_2 (R_1 R_2)/(R_1 + R_2)`
`I_1 R_1 = I_2(R_1 R_2)/(R_1 + R_2)`
`impliesI_1 = I_2 (R_2)/(R_1 + R_2)`
`5 = 6 xx (10)/(R_1 + 10) implies5(R_1 + 10) = 60`
`5R_1 + 50 = 60 , 5R_1 = 10`
`R_1 = (10)/(5) = 2 Omega impliesR_1 = 2 Omega`


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